Utils: Modernize further

Many issues, mostly in headers, were not addressed in
e38410b76c

modernize-use-auto
modernize-use-nullptr
modernize-use-override
modernize-use-using
modernize-use-default-member-init
modernize-use-equals-default

Change-Id: I320a51726db881e582b898948d53735ebb06887a
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/synchronousprocess.cpp

@@ -84,7 +84,7 @@ namespace Utils {
 // A special QProcess derivative allowing for terminal control.
 class TerminalControllingProcess : public QProcess {
 public:
-    TerminalControllingProcess() : m_flags(0) {}
+    TerminalControllingProcess() = default;
 
     unsigned flags() const { return m_flags; }
     void setFlags(unsigned tc) { m_flags = tc; }
@@ -93,7 +93,7 @@ protected:
     void setupChildProcess() override;
 
 private:
-    unsigned m_flags;
+    unsigned m_flags = 0;
 };
 
 void TerminalControllingProcess::setupChildProcess()